My simple "rules" for a all parts of a build
a) try to make on my own. if it is scale: wonderful. If not: so what.
b) if a) is negative or I'm too lazy for it: buy it.
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So i've tried to made my own shock absorbers with internal springs.
The result made from aluminium. With a minimum lubrication they works as I want up to 20 kg payload. Above this they are compressed, but that will be rare moments in the life of the dumper.
on their places